In modern lacquering units, rotational atomizers are used, as is known, in which a so-called bell-shaped disk is driven at high rotational speeds by a compressed air turbine. The bell-shaped disk, as a rule, has the shape of a truncated cone and expands in the spraying direction, wherein the coating material to be applied is accelerated axially and especially radially in the bell-shaped disk in the shape of a truncated cone as a result of centrifugal forces, so that a cone-shaped spray jet is formed on the outline edge of the bell-shaped disk. The rotational speed of the compressed air turbine is in the range of 15,000 to 80,000 rpm. At high rotational speeds of the compressed air turbine, it may happen, however, that the driving performance upon opening the main needle with a subsequent supply of coating material is not sufficient, so as to maintain constant at the desired value the rotational speed of the compressed air turbine. In this way, the rotational speed of the compressed air turbine could drop by up to 20% upon opening the main needle of the rotational atomizer, wherein the lacquering quality would be impaired.
The goal of the invention is therefore to improve a rotational speed of the rotational atomizer and eliminate a vibration of a rotatable turbine wheel to improve driving torque of the rotatable turbine wheel.